Numerical Simulation And Experiments On Throttle Devices

In the present research, numerical simulations and calibration experiments are done on throttle devices such as orifice-plate, v-cone, and spindle.In the result of two dimensional simulations, the distribution of velocity, pressure, turbulence, and surface friction in the flowfield of throttle devices is showed. It is discovered that the characteristic of the discharge coefficient is determined by the action of friction loss, vortex dissipation, and width changing of the actual throat. The spindle represents more advantages than orifice-plate and v-cone in repeatability, adapting to coming streams, non-recovered pressure loss, and long-term reliability.In the result of three dimensional simulations, the asymmetric distribution of velocity, pressure, and surface friction in the flowfield of an elbow and throttle devices downstream is showed. The measurement error in throttle devices caused by an upstream elbow is discussed.It is found in calibration experiments that the discharge coefficient of a spindle turns rapidly to a constant in a certain Reynolds Number. A plus error appears when an elbow installed upstream the spindle. The magnitude of the error is related to the installation angle of the elbow, which is between 0.56% and 1.73%. As a contrast, the error in orifice-plate in the same condition reaches as high as 17.4%. The result of experiments on non-recover pressure loss shows that the relative pressure loss of spindle drops rapidly to 0.3 and lower when Renolds Number increases, however it is as high as 0.7 for orifice-plate.